Duet Wifi always on fan connector short

  • I caused a short on fan connector (always on fan 1). It caused quite interesting light show and also some smoke. But it was not causing any bitter, familiar blue smoke but more like a old television (very old, 80's) style of smell. My board is Duet Wifi 1.0.1 version.

    I am hoping to replace the burnt component, but when I checked the board I cannot find any trace what so ever indicating which one it is.

    Is there any educated guesses available what dies first when that particular connector is shorted? (Always on FAN, the second one from the right). The smell somehow tells me that it could be capacitor, but I am not that experienced PCB killer I could say for sure.

    I have not tried to use it yet to see what parts are broken.
    I learnt that Duet Wifi is a bit too expensive power source for Fan wire problem debugging. Especially when you have 4€ adjustable power source available.

  • administrators

    Most likely you have burned out a PCB trace or a via. Is it just that always-on fan output that doesn't work, or all the fans? If it's just that one, use a multimeter to check which of the 2 pins isn't connected to the same pin on the other always-on fan connector and add a wire link on the back of the PCB to restore the missing connection.

  • Thanks,
    I have not had time to test what is still working. I'll test tomorrow.

  • At least both always on fan connectors are broken. They do measure 12V but the hotend fan does not work. Fan works when I connect it directly to POWER IN connector.

    There is no visible problems in PCB traces, at least in ones being visible.

  • Pwm fans could have problems too. I did not tried them earlier, I was setting up print fan when I shorted the board. Now I cannot get 12V regardless of jumper position.

  • administrators

    With power off, remove the fan voltage select jumper. Then use a multimeter to check continuity from the VIN side of that 3-pin header to the VIN+ terminal block, and from the centre pin of that header to the V_FAN side of the fan connectors. One of those - probably VIN - will have lost continuity due to a via burning out. Add a wire link on the back of the board to bypass it.

  • Thank you David!
    It was VIN.

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